CN1875659B - Heated laminated glazing - Google Patents

Abstract

The present invention discloses a multi-layer window glass (1) with trapezoidal configuration, which comprises a heating area (2) formed by all heating wires (3) which are laid parallel; at least two mother wires (4, 5), the ends of some of the heating wires (3) are connected with the mother wires (4, 5) parallel, and the mother wires (4, 5) are laid oppositely along the sides of the multi-layer window glass (1) in parallel; at least one mother wire (4S, 5S, 8) extends along the side of the triangle area surface area of the trapezoidal configuration; at least one outer triangle surface of the trapezoidal configuration is occupied by other heating wires (6), supplying power via mother wires (4S, 5, 5S, 8) to each heating wire (6), and each heating wire (6) is parallel to each other and parallel to the heating wire (3) in the heating area (2), and each heating wire (6) has at least two groups of heating wires which are electrically connected in series with one another. In the area of the at least one outer triangular surface, heating wires (6) located parallel alongside one another and having different lengths are combined to form groups (6.1, 6.2, 6.3) connected in parallel, and at least two of these groups are electrically connected to one another in series such that the effective wire length between the two main busbars is increased, to homogenize the heating power in the triangular surface with the heating power in the heating area.

Description

Heatable multiple panes

The invention relates to heated multiple panes, which can be heated by means of embedded wires and which are characterized by the preamble of patent claim 1 .

Description of prior art

US 5,798,499 describes a glazing of this nature with a trapezoidal profile, the outer triangular surface of which, as well as the central area of its surface, are provided with conductors arranged parallel to each other, said conductors being supplied with a heating current. The effective lengths of the conductors in the triangular surface (sides) are shorter and shorter than the conductors of approximately the same length arranged in the central area of the surface and thus have a lower resistance value for the same ohmic resistance per unit length. As a result, if no other measures are taken, relatively high currents will flow there, which will lead to unwanted and possibly unacceptable temperature peaks.

In this case, the expression approximately trapezoidal profile means a profile with one or more arcuate or curved side edges. In any event, therefore, in many such heated glazings, the longer sides of the trapezoid are curved. In contrast, the shorter (side) edges are substantially rectilinear.

The basic problem of uniform temperature distribution has been solved in various ways according to the US patents cited above.

According to an advantageous embodiment, the shorter wires in the outer triangular surfaces are made with wires of smaller cross-section and thus have a higher electrical resistance, in order to prevent local overheating as much as possible. In a variant, the side heating wires are arranged such that they are spaced apart from each other by a greater distance than the wires arranged in the central heating zone. The shorter wires are then admittedly hotter than their longer parallel wires, but at a lower heat density than in the central heating zone. The material of the multiple panes therefore still dissipates a greater amount of heat without damage. The middle section which is not heated in this configuration acts more or less as a cooling surface.

The previous patent application DE 103 16 387.5-34 also discloses another alternative to the same problem. According to an advantageous embodiment, the lateral heating wires are supplied with a lower supply voltage than the voltage applied to the wires arranged in the heating zone, because of a voltage divider or an input resistor in the busbar, or because Each heating wire on the side is powered by a separate busbar.

In another preferred embodiment, the lateral heating wires have a higher electrical resistivity than the wires arranged in the central heating area. This enables the heating wires on the sides to be supplied with the same supply voltage as the heating zone without any risk of local overheating. This can be achieved by using different materials for each wire in the heating area and for each wire on the opposite side, these different materials are also used for the results caused by materials of different length resistance despite the same wire thickness. In the case where the wires consist of the same material, for example tungsten, usually for reasons of better strength, the difference in resistance is achieved, for example, with alloys or with different diameters/cross-sectional areas.

Finally, the heating power of shorter heating wires can be adapted to low-voltage power supplies by suitable separation of the current busbars.

The above measures can be done individually or in any combination. In addition, it is no longer absolutely necessary to arrange them symmetrically in the two outer triangular surfaces, but instead the arrangements can also be different from each other if desired.

In addition, it can be admitted in principle that a reduced heating power is generated in regions of the surface which are heated by additional heating wires, since in the case of windshields and rear windshields of motor vehicles In preferred applications, the outer triangular surfaces are outside the best view of the vehicle occupants.

Furthermore, in principle, (from EP-B1-773 705, EP-B1-788294) it is known (from EP-B1-773 705, EP-B1-788294) that multiple glazings are provided over their entire Heating wire. Therefore, more costly machines and control systems must be required compared to the production of glazing described above.

Finally, a device is known in the field of thin-film heating for glazing (US 2,878,357), in which a transparent, electrically conductive coating on a glazing of trapezoidal profile is divided into several tracks, the several The rails are arranged side by side with each other and can be electrically connected in series with each other by means of busbars, which in each case can be arranged alternately at the upper and lower edges of the rails. Thus a voltage divider is formed and the same current flows in all rails. Thus, the total circulating current (including in short tracks) is limited to a value that allows it to pass through the track with the greatest resistance (and largest voltage drop). With films of the same width but different lengths, it is not possible to achieve a uniform heat distribution.

Document US 5,182,431 describes the separation of essentially parallel heating conductors of the same length into 4 groups, which are produced by screen printing or by laying individual wires, which are connected in series with additional individual busbars. Overheating in the triangular side surfaces of the trapezoidal profile of the pane is avoided due to the slightly separated heating conductors being formed between the two parallel side edges of the pane.

By suitably reducing the number of conductors in groups or in some zones of some series circuits which are best used for heating, a central zone with increased heating temperature is provided, since the maximum current flow of the heating conductors is formed here, while the heating conductors A smaller current circulates in other regions.

The applicant's document DE 101 26 869 A1 describes an asymmetrical trapezoidal multiple glazing, which can be heated by individual wires, has triangular side surfaces, said glazing is provided with conductor coils powered by two busbars, so The two busbars are arranged closely parallel to each other on one side. In the lower triangular region, the conductor loops are longer than in the right-angled region to compensate somewhat for their smaller resistance.

GB 2 091 527 describes a heatable glazing with a trapezoidal profile provided with heating conductors produced by screen printing, wherein the heating conductors extend at equal distances between two side edges which form an angle with one another. In order to prevent overheating in the region of the shorter heating conductors, according to this document a part of the heating conductors is disconnected.

Starting from the first-mentioned prior art, the technical problem of the present invention is to provide a further solution to the problem of heating the outer triangular surface of a heatable multiple pane with a trapezoidal profile as harmoniously as possible.

According to the invention, this problem is achieved by the features of claim 1 . Advantageous developments of this solution are indicated by the features of the dependent claims.

Contents of the invention

According to the invention, the application of the voltage divider already mentioned as a possible solution in the previous application can be achieved by connecting in series a plurality of heating wires connected in parallel to each other in groups, the groups being arranged side by side with each other and by means of suitable Additional current bus sections or equivalent devices are connected to each other with a small ohmic resistance. This is equivalent to an extension of the effective wire length between the two main current busbars, so that the same (external) supply voltage can be supplied to the side heating wires, and it is even possible to provide a resistance value equal to or less than that of the central heating zone . There are therefore several possible embodiments.

The solution according to the invention can advantageously be realized by means of conventional devices for placing the individual heating wires on the film to be mounted, since here, in the simplest case, the wires can always be helically arranged at equal intervals and often Parallel to each other on the membranes, the membranes are fixed on drum-shaped rotationally movable supports.

If window panes according to the invention such as these are preferably used in motor vehicles as windshields or rear windows, it is conceivable according to the invention to provide heating wires exclusively for use in this field of construction.

Further details and advantages of the inventive subject matter will become apparent from the following detailed description and from the accompanying drawings of exemplary embodiments, illustrated in simplified and not exact scale:

Figure 1 shows a first embodiment of a multilayer glazing, in which three sets of heating wires parallel to each other are interconnected in series with each other in the outer triangular region of a voltage divider; and

Figure 2 shows a variant of the first embodiment in which two sets of parallel heating wires are interconnected in series with a voltage divider in the outer triangular region.

According to FIG. 1 , the approximately rectangular heating zone 2 has heating wire groups 3 , which are laid parallel to each other along a straight line, and the heating field 2 is embedded in a heatable multilayer window with a substantially trapezoidal (arc) profile in a manner known per se. in the glass. In this case, only about half of the pane 1 is illustrated; the other half is implemented in the same way. The heating zone 2 also has an upper busbar 4 and a lower busbar 5 which are likewise embedded in the composite in a known manner.

This composite usually consists of two hard panes of glass and/or plastic material and an adhesive layer joining their surfaces together. Before the bonding layer is inserted into the multiple glazing, the heating area and the respective busbars are embedded in the bonding layer (such as a thermoplastic adhesive composed of polyvinyl butyral "PVB" or ethylene vinyl acetate "EVA"). junction film).

In the case of conductor-heated multiple panes, the individual busbars generally consist of thin and narrow metal foil strips (copper, aluminum), which are applied before and/or after the individual heating conductors are laid. The individual foil strips are pre-coated (pre-tinned) with solder and soldered to the individual conductors, while the solder must ensure that the individual (tungsten) conductors are inserted as tightly as possible. These features are known in the prior art. All busbars have negligible electrical resistance compared to the heating wires and should not heat up during operation of the heating system.

The spacing between the individual heating wires is only briefly reproduced here. Typically, the wires are laid at a very short distance (2-5 mm) from each other in order to achieve practically uniform heating of the glazing surface. In fact, they are much thinner than busbars 4 and 5 than shown here. However, by varying the spacing, the amount of surface heating power available for a predetermined wire resistance is adjusted as desired. Also, for simplicity, the illustration in this case only shows the individual wires running in a straight line. In practice, however, the wires are slightly "corrugated" in the usual way, that is to say they are laid in the shape of corrugations with a small wavelength and amplitude, since this makes them very inconspicuous (in particular reducing light diffraction effect).

Since in industrial-scale manufacture the film is helically provided with wires in a continuous manner, usually several films are laid simultaneously on a drum support (see in particular the above-mentioned document EP-B1-773705), the wires must be along their edges was cut to allow connection of the film. The small angle of inclination of the longitudinal axis of the conductors relative to the central axis of the window pane is caused by the laying of the conductors in a helical shape, which is not illustrated here for the sake of simplicity.

In a known manner, two (or more) heating zones 2 that can be powered separately are provided in the multiple pane 1 (by, for example, a division in the center of the pane), although these heating zones must of course also be connected via separate external connections connected to the corresponding voltage source. In this case, a common ground conductor can be applied for both heating zones, so that only the busbar 4 or busbar 5 has to be divided into two parts, while the rest is continuous. In the first variant, 4 external connections are required, whereas in the second variant only 3 are required.

Said external connections have been described many times in the prior art, so no time will be wasted on them here. In conclusion, in the configuration shown in FIG. 1 it is possible to arrange the connecting elements in adjacent positions at both lower corners of the multiple pane 1 or at one lower corner.

The upper busbar 4 runs parallel to the upper curved edge of the multilayer glazing 1, bends the upper busbar 4 at two mutually adjacent corners, and is then extended by branches 4S-in a manner known per se in the visible part of the multilayer glazing 1 Extends parallel to that side for most of the length of the left side. Until the lower busbar 5. The lower busbar 5 extends virtually over the entire length of the arcuate lower edge of the multiple pane 1 at an approximately constant distance from the edge of the multiple pane 1 .

The right side (not visible here) of the multiple pane 1 is generally symmetrical. In the following, therefore, only the details of the routing and laying of the conductors for the left triangular side region of the pane 1 will be discussed.

The side heating conductor group 6 is arranged in the outer triangular region of the multiple pane 1 , to the left of the heating region 2 . The vertical dashed lines represent the limits between the central heating zone 2 and the side conductors 6 . Their length tapers from right to left like a harp. So shorter wires have less ohmic resistance if the same material is chosen.

According to the invention, the multilayer glazing is equipped in the left outer triangular area with a series circuit of three active sets of heating conductors arranged parallel to each other (for illustration purposes, the groups are indicated by dotted ellipses connected). These heating wires are preferably composed of the same material. However, other materials can also be used in order to better suit the localized heating power. However, from the viewpoint of the above-mentioned manufacturing technology, the change of the material when laying the individual wires is rather expensive.

To the left of the dotted dividing line between the central heating area 2 and the side areas of the multiple glazing 1, a relatively long first group 6.1 of the heating wires is electrically connected at height to the branch 4S of the busbar 4 (in this example with 5 wires). Their lower ends are electrically connected to an additional part 7 of the busbar, said part 7 being electrically independent from the busbar 5, in particular without its own external connections. It is arranged parallel to the busbar 5 at a small distance and serves only to allow the current circulating in the group 6.1 to flow to the second group 6.2 of heating wires (medium length; in this case 4 wires), which 6.2 Extends from the bottom (section 7) to a further section 8 of separate busbars.

Said further portion 8 is arranged along the left edge of the pane 1, axially aligned with the branch 4S, constituting, so to speak, its extension, but not directly connected to this branch. However, like part 7, further part 8 has no external electrical connections of its own. It can easily be formed by interrupting a long branch 4S as shown in FIG. 1 at an interruption point T between two heating wires in different groups. Here this break point is also shown with an exaggerated width.

A third group 6.3 of very short active wires now only runs from the part 8 of the busbar to the busbar 5 and thus forms the last element in the series circuit.

Assuming that the heating current circulates through said wires from busbar 4 to busbar 5, in the first group 6.1 the heating current circulates from top to bottom (busbar 7), in group 6.2 it circulates upwards (to busbar 8), and In group 6.3 the heating current circulates again from top to bottom.

The total current circulating in the heating wires on each side of the three groups is determined by the group with the greatest ohmic resistance. Because the total resistance of a group depends not only on the length of the individual wires, but also on the number of wires in a group and, if desired, on their resistance per unit length, those skilled in the art can combine Very uniform heating in this region is obtained very easily with groups 6.1-6.3. Furthermore, it is of course possible to form one or more passive wires in groups 6.1 , 6.2 and/or 6.3 which do not provide heating power, with a plurality of interruptions of a form known per se.

If the same wire material and the same number of active wires are used to implement the three groups, the group 6.1 with the longest wires will of course have the largest defined resistance for the total current at a given voltage, and this largest The defined resistance is in particular significantly greater than the resistance of the group 6.3.

The test window pane shown in FIG. 1 used a heating wire 3 with a resistance of 150 Ω/m and a heating wire 6 with a resistance of 100 Ω/m in the heating zone 2 . The side heating wires thus have a lower resistance per unit length than the individual heating wires 3 . It can be seen from the thermograms that the division into three groups will result in a very good homogenization of the triangular surfaces with the heating zone 2 - except for the outer group 6.3 which, in the selected configuration, will obviously Very little current is passed so that it doesn't even just get hot.

However, in a configuration in which the electrical resistances of the three groups are identical to one another, this will not necessarily result in the same heating power being produced everywhere.

FIG. 2 shows, in a modified form, the embodiment of FIG. 1 divided into two groups of parallel heating wires 6.1 and 6.2. This configuration requires only a single additional busbar 7 which is again arranged parallel to the busbars 5 at a small distance. However, this requires extending this busbar 5 around the lower left corner of the multiple glazing 1 with a branch 5S, similar to the branch 4S of the upper busbar (an equivalent measure, with small ohmic resistors at the upper ends of the wires in group 6.2 Commonly connected to the bus bar 5).

In this exemplary embodiment, the two branches 4S and 5S extending along the same axis end approximately immediately next to each other in the middle of the height of the multiple glazing 1 or in the middle of the height of the sides of the glazing. If desired, the outer connections of the two busbars 4/4S and 5/5S directly adjacent to each other can be arranged at this location on both sides of the space T.

In this case, however, it is also possible to arrange the external connections of the busbars 4 and 5 at the lower or upper corner of the window pane 1 (contrary to the illustration). For this purpose, branch 4S should run parallel to additional busbar 8 in FIG. 1 , or would have to run parallel to 5S to the lower left corner in FIG. 2 .

In the structure shown in FIG. 1, the group 6.1 starts from the branch 4S and ends in the additional busbar section 7. From this section, the second group 6.2 goes up again and ends in branch 5S. This also applies to the current, for which the above is important when again assuming that the current circulates from busbar 4 to busbar 5 . In group 6.1 the current flows downwards and in group 6.2 it flows upwards.

For the detailed construction of the two groups 6.1 and 6.2 of FIG. 2 , what has already been described for the groups 6.1-6.3 of FIG. 1 is equally important. The side heating wire 6 is again embodied with a heating wire 3 having a resistance of 100 Ω/m and a resistance of 150 Ω/m.

The best results for temperature recording of all samples were achieved with the embodiment shown in FIG. 2 . A complete homogenization of the heating power over the entire surface of the heated multiple pane can be achieved, exactly equally well whether after 4 minutes or 8 minutes of heating. The power rating at 12V is 477W (about 41A total), so it's well within the user manual. No unacceptable heat spikes occurred at any location.

Regarding the above-mentioned method of laying the various conductors, it should be noted that the conductors directly connecting the additional busbar 7 in Figures 1 and 2 to the busbar 5 must be cut; Remove from the composite. This results in the fact that no conductors are exposed in the narrow intermediate space between busbar 7 and busbar 5 , as is illustrated in the two figures for the sake of simplicity.

The edges of the multiple panes 1, and thus also the busbars 4 and 5 and 7 and 8, or their external connections, can be colored in a known manner with opaque colored The frame is covered, it is not illustrated here so that the individual busbars can be seen.

Finally, it should be pointed out that the external electrical connections on the busbar parts 7 and 8 do not have to be used for the heating function, e.g. antenna potentials for different applications can be connected to additional busbars, for example using the multiple glazing (additionally) as Antenna window glass, like said busbars 4 and 5 and their branches. For example, a separate external connection with respect to the isolation of the busbar 5 should then cross the busbar 5 in order to contact the busbar 7 from the outside.

Claims (18)

1. Heatable multilayer glazing (1) with a trapezoidal profile and with: a heating zone (2) embedded in the composite part, the heating zone is formed by heating conductors (3) arranged next to each other and at least two busbars (4, 5), one above and the other below, which connect the ends of a plurality of heating wires (3) to each other, said heating wires (3) running along the multilayer window The sides of the glass (1) are arranged in opposite positions, wherein the branches of at least one busbar extend along the sides of the outer triangular surface area of the trapezoidal profile, at least one outer triangular surface area of the trapezoidal profile is provided with additional heating wires (6), The further heating conductors (6) are oriented parallel to one another and parallel to the heating conductors (3) of the heating zone (2), the further heating conductors (6) are supplied with power from the bus bar or a branch of the bus bar, characterized in that at least In the region of an outer triangular surface, said further heating wires (6) arranged parallel to each other and having different lengths are brought together in groups (6.1, 6.2, 6.3) connected in parallel, at least two of these groups being connected in series with each other, The effective wire length between the two main current busbars is increased in order to match the heating power in the triangular surface to the heating power in the heating zone (2). 2. Heatable multiple glazing as claimed in claim 1, characterized in that additional busbars (7, 8) are used for the connections between the two groups (6.1, 6.2; 6.2, 6.3). 3. Heatable multiple glazing as claimed in claim 2, characterized in that the additional busbars (7, 8) are arranged parallel to the busbars (5) or branches (4S) of the busbars. 4. A heatable multiple pane as claimed in claim 1 or 2 or 3, characterized in that the number of conductors in a single group (6.1, 6.2, 6.3) is different or the same. 5. Heatable multiple glazing as claimed in any one of claims 1-3, characterized in that the branches (4S, 5S) of the two busbars (4, 5) follow the outer triangular surfaces of the trapezoidal profile At least one side of the region extends and terminates on both sides of the interruption point (T). 6. Heatable multiple glazing as claimed in claim 5, characterized in that the external connections of the two busbars (4, 5) are arranged in branches (4S, 5S) on both sides of the interruption point (T) in the free end region of the . 7. Heatable multiple glazing as claimed in any one of claims 1-3, characterized in that the external connections of at least two busbars (4, 5) are connected to A corner location. 8. Heatable multiple glazing as claimed in any one of claims 1-3, characterized in that at least one bus bar (4, 5) is divided into two electrically isolated parts, each of which With external connections. 9. The heatable multiple pane as claimed in claim 1 , characterized in that the further heating wire ( 6 ) has an ohmic resistance per unit length equal to that of the central heating zone ( 2 ) The ohmic resistance per unit length of each heating wire (3) in is different. 10. The heatable multiple pane as claimed in claim 9, characterized in that the further heating conductors (6) have a lower electrical resistance than the heating conductors (3) in the central heating zone (2) . 11. Heatable multiple glazing as claimed in any one of claims 1-3, characterized in that one or more of said further heating wires (6) are cut in order to produce single or multiple Passive wires that do not provide heating power. 12. The heatable multiple pane as claimed in any one of claims 1-3, characterized in that the heating wire (3) and the further heating wire (6) are arranged in a helical shape on the bracket on the film. 13. The heatable multiple pane as claimed in claim 1 , characterized in that the heating wire ( 3 ) and the further heating wire ( 6 ) are corrugated and of short amplitude Corrugated with respect to their longitudinal axis, which lays substantially straight. 14. Heatable multiple glazing as claimed in any one of claims 1-3, characterized in that one or more busbars are provided with individual external connections isolated with respect to said busbars. 15. The heatable multiple pane as claimed in claim 1, characterized in that the edge region is provided with an opaque colored band. 16. Heatable multiple glazing as claimed in claim 15, characterized in that said opaque colored strip optically conceals said busbars. 17. Use of a heatable multiple pane as claimed in one of the preceding claims in a motor vehicle. 18. Use of a heatable multiple pane as claimed in claim 17, characterized in that the heatable multiple pane is used as a windshield or rear windshield.

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